Aromatic Compounds

Question 1

What are aromatic compounds?

Answer 1

Cyclic compounds, containing some number of conjugated double bonds and have an unusually large resonance energy

Question 2

What structure did the kekulé structure fail to explain?

Answer 2

1,2-dichlorobenzene

Question 3

What is the hybridization of the carbons in benzene?

Answer 3

Sp2 hybridized

Question 4

What the shape of benzene?+ What are the CCC bond angles?

Answer 4

CCC bond angles are 120 degrees and benzene is a planar structure

Question 5

What is the length of carbon-carbon lengths in benzene?

Answer 5

139pm, intermediate between single and double carbon bonds

Question 6

What happens to the electrons in the overlapping p orbitals in benzene?

Answer 6

These 6 pi electrons are delocalised over the six carbons

Question 7

What are annulenes?

Answer 7

Cyclic hydrocarbons with alternating single and double bonds

Question 8

What are nonaromatic compounds?

Answer 8

Cyclic compounds that do not have a continuous , overlapping ring of p orbitals and may be nonplanar

Question 9

What are antiaromatic compounds?

Answer 9

Compounds that are cyclic, conjugated with overlapping p orbitals around the ring but the delocalized pi electrons over the ring increases its electronic energy

Question 10

What is hekules’s rule?

Answer 10

If the number of pi electrons in a cyclic system is (4N+2) the system is aromatic

If the number of pi electrons is (4N) in the system then it is antiaromatic

Question 11

What does the ortho- name mean in relationship to the structure of the molecule

Answer 11

1,2-disubstituted

Question 12

What does the meta- prefix mean in relationship mean in relationship to the structure of the molecule?

Answer 12

1,3-disubstitued

Question 13

Shaft does the para- prefix mean in relationship to the structure of the molecule?

Answer 13

1,4-disubstituted

Question 14

What are the aromatic requirements

Answer 14

• cyclic structure with conjugated pi bonds
• each atom in the ring must have an unhybridized p orbital
• the unhybridized p orbitals must overlap continuously around the ring
• delocalization of the pi electrons over the ring must lower the electronic energy

Question 15

What are the requirements for heckule’s rule to apply?

Answer 15

Must be aromatic or antiaromatic- cyclic compound with a continuous ring of. Overlapping p orbitals

Question 16

What is the difference between the phenyl and benzoyl group?

Answer 16

Benzyl- additional carbon attached to the ring

Phenyl- general attachment to the ring

Question 17

What is the bond order of benzene?

Answer 17

1.5

Question 18

What is the annulene name for benzene?

Answer 18

6-annuulene

Question 19

What is the annulene name for cyclobutadiene?

Answer 19

4- annulene